I'm also seeing really bad framerates here. It seems to get worse with every new location, and restarting the game in whatever location I'm in fixes it 'til I go somewhere new again. And I know my system is capable of running the game just fine. Example:
- Start game, play intro. Framerate is top notch.
- Intro sequence runs
- Load screen
- Cutscene on the street plays, framerate is bad (I estimate 15-20 fps).
- Save and quit
- Resume save, framerate is great again.
- Enter Stinky's. Framerate is worse (back to 15-20)
- Exit Stinky's. Framerate is worse still.
At any point, restarting the game makes it all better, until the next location change. That kind of leads me to think 'resource leak' and not an incapable system. Also, I rebooted into Windows 7 via Boot Camp and had no such problems at the same settings.
Model: Mac Pro (MacPro3,1)
CPU: Dual 2.8GHz Quad-core Xeon
Video card: GeForce 8800GT 512MB